#include <mpi.h>
#include <iostream>

int main(int    ac,
         char * av[]) 
{

  MPI_Init(&ac,
	   &av); 

  int rank;
  int size;
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  MPI_Comm_size(MPI_COMM_WORLD, &size);
  MPI_Comm_set_errhandler(MPI_COMM_WORLD, MPI_ERRORS_RETURN);

  int bufferSize = 2000;
  int * sendBuffer = new int[bufferSize];  
  int * recvBuffer = new int[bufferSize];

  MPI_Request * mpiSendRequests = new MPI_Request[size - 1];
  MPI_Request * mpiRecvRequests = new MPI_Request[size - 1];

  //
  // post receives
  //
  int recvCount = 0;
  for(int i=0; i<size; ++i) {
  
    if(i != rank) {

      int error = MPI_Irecv(recvBuffer,
			    bufferSize,
			    MPI_INT,
			    i,
			    0,
			    MPI_COMM_WORLD,
			    &(mpiRecvRequests[recvCount++]));
      
      if(error != 0) {
	std::cout << "Irecv Error " << error << std::endl;
      }

    }
    
  }

  //
  // post sends
  //
  int sendCount = 0;
  for (int i = 0; i < size; ++i) {

    if (i != rank) {

      int error = MPI_Isend(&(sendBuffer[0]),
			    bufferSize,
			    MPI_INT,
			    i,
			    0,
			    MPI_COMM_WORLD,
			    &(mpiSendRequests[sendCount++]));

      if(error != 0) {
	std::cout << "Isend Error " << error << std::endl;
      }

    }
  }

  //
  // wait for completion
  // 
  MPI_Status * sendStatus = new MPI_Status[size - 1];
  MPI_Status * recvStatus = new MPI_Status[size - 1];

  int sendError = MPI_Waitall(size - 1, mpiSendRequests, sendStatus);

  if(sendError != 0) {
    std::cout << "SEND ERROR " << sendError << std::endl;
    for(int i=0; i<size-1; ++i) {
      std::cout << i << " " << sendStatus[i].MPI_ERROR << std::endl;
    }
  }

  int recvError = MPI_Waitall(size - 1, mpiRecvRequests, recvStatus);

  delete [] sendBuffer;
  delete [] recvBuffer;

  if(recvError != 0) {
    std::cout << "RECEIVE ERROR " << recvError << std::endl;
  }

  MPI_Barrier(MPI_COMM_WORLD);
  if(rank == 0) {
    std::cout << "HERE" << std::endl;
  }
  
  MPI_Finalize();

}